Translation problem (from English to Norwegian)

Hello! If you can help me with this problem, I would be very grateful. I use the page lines PlatformPro and latest version of Wordpress (3.0.1), but I have big problems to install the translation file in my landuage (norwegian).
Where can I fint the wp.config.filen I need to change? Or how can I easiest possible install Norwegian on my blog? I am a novice, novice with capitalletters. (In advance, thank you for all the answers and sorry about my spelling ...)
Sincerely, Bjornar (novice norwegian)
:-)